Fire sensing system, process for sensing fire and environment monitor

Abstract

A fire sensing system, a process for sensing a fire and an environment monitor are disclosed. The system includes infrared sensors with sensing wavelength bands sensing an infrared radiation from an infrared source. One of the sensing wavelength bands is a CO 2 -molecular resonance radiation wavelength band. The system determines whether a disastrous fire occurs or not on the basis of outputs of the sensors and a change in a ratio of the outputs. The process computes the temperature of the infrared source from a ratio of outputs of infrared sensors with at least two sensing wavelength bands of an infrared radiation from a monitored area, produces the intensity of infrared radiation of either of the bands from the computed temperature and computes a heating area from the intensity and the output of a corresponding infrared sensor. The process determines the progress of a fire. The monitor produces a control signal to an air conditioner or room heater-and-cooler from outputs of sensors and an output of a thermometer.

What is claimed is: 
     
       1. A fire sensing system, comprising: a plurality of band-pass filters separating infrared radiation from a source of infrared radiation into a plurality of wavelength bands;   an infrared sensor sensing an infrared radiation which has passed through each of said band-pass filters, one of the wavelength bands comprising a CO 2  -molecular resonance radiation wavelength band;   a signal processor determining whether a disastrous fire occurs or not in response to outputs of the infrared sensors and a change in a ratio of the outputs of the infrared sensors; and   a chopper periodically chopping said infrared radiation from said source of infrared radiation in order to provide said infrared radiation to said infrared sensors.   
     
     
       2. A fire sensing system as recited in claim 1, further comprising an infrared sensor for a band of 1-16 μm wavelength. 
     
     
       3. A fire sensing system as recited in claim 1, wherein the pass band of each of said band-pass filters excludes a 5-8 μm wavelength band of infrared radiation. 
     
     
       4. A fire sensing system as recited in claim 1, wherein said signal processor detects the outputs of said infrared sensors synchronous with two periodical signals which are synchronous with the rotation of said chopper, said periodical signals having two 90-degree different phases and said signal processor then produces a mean square of the resulting synchronization-detected signals. 
     
     
       5. A fire sensing system, comprising: a plurality of band-pass filters separating infrared radiation from a source of infrared radiation into a plurality of wavelength bands;   an infrared sensor sensing an infrared radiation which has passed through each of said band-pass filters, one of the wavelength bands comprising a CO 2  -molecular resonance radiation wavelength band;   a signal processor determining whether a disastrous fire occurs or not in response to outputs of the infrared sensors and a change in a ratio of the outputs of the infrared sensors, and   wherein said signal processor computes the blackbody radiation intensity of the sensing band of one of said infrared sensors which senses a CO 2  -molecular resonance radiation band in response to said one of said infrared sensors, and said signal processor compares the computer blackbody radiation intensity with an output of said one of said infrared sensors in order to sense CO 2  -molecular resonance radiation and determines an occurrence of a disastrous fire when sensing the CO 2  -molecular resonance radiation.   
     
     
       6. A fire sensing system as recited in claim 5, wherein said signal processor comprises a filter passing a signal of a predetermined frequency of the sensing outputs of said infrared sensors, a comparator comparing said signal with a predetermined reference level, and a microcomputer determining the existence of an uncontrolled fire in response to a signal produced by the comparator. 
     
     
       7. A process for sensing a fire, comprising the steps of: computing the temperature of an infrared source from a ratio of outputs of a plurality of infrared sensors sensing at least two wavelength bands of an infrared radiation from a monitored area;   computing the intensity of infrared radiation of one of the wavelength bands from said computed temperature;   computing a heating area from the intensity of the infrared radiation and an output of an infrared sensor sensing said one of the wavelength bands;   utilizing one of the infrared sensors for sensing a CO 2  -molecular resonance radiation wavelength band;   computing the blackbody radiation intensity of the infrared source in a CO 2  -molecular resonance radiation wavelength band from the temperature and the heating area of the infrared source both computed from an output of the other infrared sensor in accordance with said temperature and heating area computing steps; and   comparing the computed blackbody radiation intensity with an output of said one of said infrared sensors sensing CO 2  -molecular resonance radiation and determining an occurrence of a disastrous fire when sensing the CO 2  -molecular resonance radiation.   
     
     
       8. A process for sensing, a fire as recited in claim 7, wherein a selection determining which of the outputs of said infrared sensors are computed depends on a sensed target temperature. 
     
     
       9. A process for sensing a fire as recited in claim 7, further comprising the step of driving an alarm when determining an occurrence of disastrous fire. 
     
     
       10. A process for sensing a fire as recited in claim 7, further comprising the step of displaying a computed heating area of the infrared source on a monitor. 
     
     
       11. An environment monitor, comprising: a plurality of band-pass filters separating infrared radiation from a monitored space into a plurality of wavelength bands;   an infrared sensor sensing infrared radiation passing through each of said band-pass filters, one of the wavelength bands comprising a CO 2  -molecular resonance radiation wavelength band;   a signal processor determining the occurrence of fire and computing a temperature of the infrared radiation from the monitored space from outputs of the infrared sensors of the wavelength bands and a change in a ratio of said sensing outputs; and   a chopper periodically chopping the infrared radiation from the infrared source in order to provide the infrared radiation to said infrared sensors.   
     
     
       12. An environment monitor as recited in claim 11, further comprising an infrared sensor for a 1-16 μm wavelength band of infrared radiation. 
     
     
       13. An environment monitor as recited in claim 11, further comprising a contact type temperature sensor for measuring an indoor air temperature and wherein said signal processor produces a signal controlling an air conditioner in response to outputs of said contact type temperature sensor and said infrared sensors. 
     
     
       14. An environment monitor as recited in claim 11, further comprising a contact type temperature sensor for measuring an indoor air temperature and wherein said signal processor produces a signal controlling a room cooler and a room heater in response to outputs of said temperature sensor and said infrared sensors. 
     
     
       15. An environment monitor as recited in claim 11, wherein the pass band of each of said band-pass filters excludes a 5-8 μm wavelength band of infrared radiation. 
     
     
       16. A process for sensing a fire, which comprises the steps of: computing the temperature of an infrared source from outputs of a plurality of infrared sensors sensing at least two different wavelengths by comparing the ratio of said outputs;   computing the blackbody radiation intensity of at least one of said different wavelengths from said computed temperature;   computing a heating area of said infrared source from said blackbody radiation intensity and output from said infrared sensor sensing said at least one of said different wavelengths; and   determining the existence of a uncontrolled fire from changes in said computed temperature and said computed heating area.   
     
     
       17. a process for sensing a fire as recited in claim 16, further comprising the steps of: utilizing one of said plurality of infrared sensors for sensing radiation at a wavelength corresponding to CO 2  -molecular resonance;   computing the blackbody radiation intensity of said wavelength corresponding to CO 2  -molecular resonance from said computed temperature and said computed heating area; and   comparing computed blackbody radiation intensity of said wavelength corresponding to CO 2  -molecular resonance with an output of said infrared sensor sensing radiation at a wavelength corresponding to CO 2  -molecular resonance to determine the existence of a flaming infrared source.   
     
     
       18. A process for sensing a fire as recited in claim 16, further comprising the step of displaying said heating area on a display monitor. 
     
     
       19. A fire sensing system, comprising: a plurality of band-pass filters separating infrared radiation from a source of infrared radiation into a plurality of wavelength bands, wherein one of said band-pass filters passes a CO 2  -molecular resonance radiation wavelength band;   a plurality of infrared sensors sensing said separated infrared radiation which has passed through each of said band-pass filters;   a signal processor for determining a temperature and a heating area of said source of infrared radiation and determining the existence of an uncontrolled fire based on changes in said temperature and said heating area; and   a signal processor for determining the existence of a flame in said source of infrared radiation by comparing an output of a sensor sensing said CO 2  -molecular resonance radiation wavelength with a value predicted by said temperature and said heating area for determining the existence of an uncontrolled flaming fire.   
     
     
       20. A fire sensing system, comprising: a plurality of band-pass filters separating infrared radiation from a source of infrared radiation into a plurality of wavelength bands;   a plurality of infrared sensors sensing said separated infrared radiation which has passed through each of said band-pass filters;   a signal processor for determining a temperature and a heating area of said source of infrared radiation and determining the existence of an uncontrolled fire based on changes in said temperature and said heating area; and   a chopper periodically chopping said infrared radiation from said source of infrared radiation in order to provide said infrared radiation to said infrared sensors.